GB804662A - Improvements in sensitive materials for colour photography - Google Patents

Abstract

804,662. Colour photographic materials. KODAK, Ltd. July 20, 1956 [July 26, 1955], No. 22496/56. Class 98(2) A support bears at least two superposed differentially sensitive silver halide emulsion layers each containing a different non- diffusing colour coupler and each containing a nucleating agent for catalyzing the reduction of or for precipitating dissolved silver salts, and also containing a non- diffusing non-colour forming reducing agent. The emulsion layers may be of the usual red/cyan, green/magenta and blue/ yellow sensitivity/coupler sequence starting from the support and may all be fast, in which case a yellow filter is included beneath the upper layer, or the lower layers may be slow, with omission of the yellow filter. The material may be exposed, black and white developed, acidstopped, washed, then directly colour developed with a developer including a silver halide solvent, stopped, washed, bleached, washed, fixed and washed; thus effecting reversal without re-exposure before the colour development. An example describes production and processing of such material in full detail, using colloidal silver as nucleating agent and 2 : 5-di-sec octyl hydroquinone as the reducing agent referred to above. Numerous similar agents of both types, and also colour formers for the layers are quoted. A somewhat similar procedure in which the non-diffusing. non-colour forming reducing agent is not used, but requiring the presence of additional, barrier, layers containing nuclei between the emulsion layers to check diffusion of silver salts dissolved during colour development is described. Specifications 545,448, 547,064, 562,205, 680,488 and 804,661 are referred to.